Question

An electrical heater is rated $4\mathrm{kW},220\mathrm{V}$. Find the cost of using this heater for $12\mathrm{h}$, if one $\mathrm{kWh}$ of electrical energy cost $₹3.25$

Answer 1

Step 1 Given data:

Power of electrical heater $=4kW=4000W$

Voltage of electrical heater $=220V$

Time $=12h$

The cost of one $\mathrm{kWh}$ of electrical energy is $₹3.25$

Step 2 Calculating electrical energy consumed:

As we know that,
The formula for finding electrical energy consumed is $=\frac{\text{power (in watt)}\times \text{Time (in hr)}}{1000}$

So, for determining the consumed electrical energy we will put the value of power and time in the above formula.

Thus we will get,

$$\begin{gathered} =\frac{4\times 1000\times 12}{1000} \\ =48\mathrm{kWh} \end{gathered}$$

$\therefore$ Cost of electrical energy $=(48\times 3.25)=₹156$

Hence, the cost of electrical energy will be $₹156$